Origio Scientia

When Sirius fell through the veil, the last thing he expected was a second chance at life. A mysterious encounter with the one styling himself the "gatekeeper" leads him on a journey sideways in time to a dark reality where an even greater threat foreshadows the world. A world where Grindlewald never fell but Voldemort never rose. And this time there's no Dumbledore to save them all.